Glycosphingolipids (GSLs) are components of the cell membrane that are of interest because of their properties as receptors and antigens, and as markers of cellular differentiation. This project includes studies of the basic chemistry and immunological properties of GSLs, glycolipid antigens as markers of functional subsets of human lymphocytes, and the genetics and immunochemistry or erythrocyte blood group antigens. We are developing new high-performance liquid chromatographic (HPLC) techniques for analysis of neutral glycolipids that contain more than five sugars, and an autoradiographic technique for analysis of mono- and disialogangliosides. In our studies of human lymphocytes we are using purified antibodies to a number of GSLs, antibodies to immunoglobulin light and heavy chain determinants and monoclonal antibodies to monocyte, Ia and T cell antigens, and performing immunofluorescence studies by means of the fluorescence-activated cell sorter. Our objectives are to use these markers to identify functional subsets of normal blood lymphocytes, to characterize B cells that are arrested in different stages of maturation, and to develop immunological criteria for classifying B lymphocytes of patients with chronic lymphatic leukemia. Our studies of erythrocyte antigens include purification of the Lub antigen of the Lutheran blood group system, and identification of the alterations that take place in the major neutral glycolipids of the erythrocyte in the course of differentiation from fetal to mature cells.